Abstract

Hepatitis A virus, unlike hepatitis B virus, has rarely been associated with extrahepatic features. Two patients developed relapsing hepatitis A complicated by arthritis in both cases and cutaneous vasculitis in one. Both patients had cryoglobulinemia, with cryocrit values of 4.3% and 8.6%. Serologic studies showed that the cryoglobulin consisted of polyclonal IgM and IgG. The washed cryoglobulin was analyzed by sucrose density gradient ultracentrifugation under neutral (pH 7.4) and acidic (pH 2.8) conditions. Enzyme-linked immunosorbent assay techniques were used to characterize the native and dissociated cryoglobulin. The cryoglobulin contained acid-dissociable IgG complexes greater than 19S, and high molecular weight rheumatoid factors of both IgG and IgM isotypes that could be dissociated to 7S and 19S forms, respectively. Dissociation of the cryoglobulin augmented 7S anti-hepatitis A virus IgG 2.27-fold, but augmented total 7S IgG only 1.12-fold, suggesting enrichment of antiviral antibody in the cryoglobulin.